Extraction of butadiene



,am J /7 /21 "e v f los; n f 1623 .N

EXTRACTION OF BUTADIENE Filed Oct. 31, 1939I (9 42; L /2- L SPe/vr GAS k ExTzAcv-ozz.

l l /ra wak h :@:z I

EXTRAc-rova ABS on En 2, COQLER COOLER I 19 :cHLcaR/p .S7-RAGE d' 7A NK .I

Patented Nov. 27, 1945 EXTRACTION F BUTADIENE Egi V. Fasce and LouisvE. Pirkle, Baton Rouge, La., Vassignors, by mesne assignments, to Jasco, Incorporated, a corporation of 'Louisiana Application October 31, 1939, Serial No. 302,084

2 Claims.

This invention relates to the extraction and segregation of diolens from gas mixtures and particularly to the separation of diolens from unsaturated and saturated hydrocarbon gases and other gases.

Distilling a mixture of saturated hydrocarbons and unsaturated hydrocarbons to fractionally separate the saturated hydrocarbons from the unsaturated hydrocarbons is not feasible. The separation of olens or unsaturated hydrocarbons from saturated hydrocarbons and other compounds of the same boiling ranges by the use of cuprous salts, such as cuprous chloride, in unsaturated aqueous hydrochloric acid or in ammoniacal solutions is known, but the further separation of the unsaturated hydrocarbons into olens and diolens was not heretofore accomplished without great diculties.

An object of this invention is to separate diolens from a mixture of saturated and unsaturated hydrocarbon gases and other gases and to concentrate the separated diolens.

These and other objects of the invention will be understood on reading the following description with reference to the accompanying drawing.

Petroleum crude oils or fractions thereof, when subjected to high temperatures, break down or crack" to form hydrocarbon compounds having less number of carbon atoms to the molecule. The hydrocarbon compounds having not over 5 carbon atoms to the molecule are normally gaseous at atmospheric temperature and consist of a mixture of both saturated hydrocarbons and unsaturated hydrocarbons. These normally gaseous fractions of hydrocarbons are fractionally distilled to segregate into hydrocarbon fractions containing substantially the same number of carbon atoms to the molecule.

A dilute gas consisting substantially. of hydrocarbons containing 4 carbon atoms to the molecule and composed of 21% of butadiene, 11% of isobutylene, 41% of normal butylene and 27% of butane is passed through pipe I into the bottom of tower 2 into which is passed from storage tank 3 by means of pump 4 and pipe 5 a mixture of 20% cuprous chloride, 32.5% of mono-ethanolamine hydrochloride, 20% of mono-ethanolamine, and 27.5 of water. This cuprous chloride solution is first cooled by means of heat exchanger 6 to a temperature of 50 F. and then passed through pipe 8 into the top of tower 2 in countercurrent flow to the butadiene-containing gas. The spent gas is removed from the tower by means of pipe 9 and contains generally about 14% of 'isobutylene, 47% of normal butylene, and 37% of butane,

desorber together with less than about 2% of butadiene. The saturated cuprous chloride solution is then passed through pipe I0 and heat exchanger 6 and through pipe I I into a desorber I2 which is maintained at a temperature between 150 and 180 F. by means of steam coils at the bottom of the desorber. After removal of the unsaturated hydrocarbons, the cuprous chloride solution is passed through pipe I3 and Water-cooled exchanger Ifl and pipe I5 into cuprous chloride storage tank 3. The temperature at which this is cooled is about F.

The unsaturated hydrocarbons separated from the cuprous chloride solution pass through outlet I6 into a second tower extractor Il. The composition of the gas is generally about 92% butadiene, 1% isobutylene, 6% normal butylene and 1% butane.

A second charge of the cuprous chloride solution from tank 3 is passed by means of pump IB and pipe I9 through heat exchanger 20 and pipe 2I into the upper part of second extraction tower where it passes in countercurrent flow to the unsaturated hydrocarbons obtained from the rst I2. The spent gases are removed through pipe 22 and are returned to inlet pipe I. The composition of this gas is generally about 13% of isobutylene, 82% of normal butylene, and 5%` of butadiene. The saturated cuprous chloride solution is then passed through pipe 23 to heat exchanger 20 and pipe 24 into the second desorber 25 where the temperature is maintained by means of a steam coil at the bottom of the tower at about 150 to 180 F. A butadiene gas product is removed there by means of pipe 26 and contains about 99% of butadiene and 1% of butylene. The gas-free cuprous chloride solution is then returned through pipe 21, water cooler 28 and pipe 29 to cuprous chloride storage tank 3.

The quantities of cuprous chloride used in the rst extractor are about 205 gallons per pound mol of butadiene, while in the second extractor gallons of the cuprous chloride solution are used per pound mol of butadiene, that is, a total of 330 gallons of the cuprous chloride solution perI pound mol are used in the two-stage operation.

The absorption of the gas in the cuprous chloride solution is at a temperature not over 50 and the recovery of the gas from the cuprous chloride solution is obtained at temperatures generally varying from to 180 F. This operation may be conducted at elevated pressures, although, when operating at pressures above 250 pounds per square inch, the eiiiciency of the process suffers.

The above example wasl given for illustration only and it is not intended to limit the invention to the speciiic composition of the absorbent used. Any absorbent may be used that has high butadiene selective absorbentproperties, for example, the following basic solutions containing either 20% cuprous chloride, 30% mono-ethanolamine, and 50% ethylene glycol; or 20% cuprous chloride, 20% ammonium chloride, 30% mono-ethanolamine, and 30% water. An acidic solution may also be used, such as one composed of 16.7%, Y,

cuprous chloride, 50% Lformamide 12% hydrochloric acid, and 21.3% Water.

We claim:

1. A continuous methodofV segregating and,

concentrating butadiene which comprises contacting a hydrocarbon fraction containing 4 carbon atoms to the molecule and butadiener witha cuprous chloride solution consisting of 16.7% cuprous chloride, 50% formamide, 12% hydrollSf 2,389,658 l l. v

chloric acid and 21.3% Water, separating the cuprous chloride solution with butadiene dissolved therein, subjecting said cuprous chloride solution to heat to expel the butadiene, contacting the expelled butadiene with another cuprous chloride solution of the same composition, separating the said cuprous chloride solution and recovering the butadiene dissolved therein by subjecting to heat.

2. A method of segregating and concentrating butadiene which comprises, contacting a hydrocarbon fraction containing four carbon atoms to the molecule and butadiene with a cuprous chloridewsolution consisting of 16.7% cuprous chloride, 50% formamide, 12% hydrochloric acid and 21.3% water, separating the cuprous chloride solution with butadiene dissolved therein, and heating the separated solution to recover the butadiene;

EGI V. FASCE. LOUIS E. PIRKLE. 

